I think you mean Bertrand, not John. And bertrand's power was the ability to manipulate genetic material (another form of matter) so that does fall into the matter based concept of conduits, just the not the "normal" style of conduits. They also mention in Second Son that the ability to manipulate organic matter was possible (so once agian transformations and such of the physical nature into more bestial aspects is possible). The Blood Festival is also not canon to the Infamous universe (too my knowledge, I could be wrong about this) so the abilities produced within that DLC is not actually part of the universe and was just something for the players to enjoy, not take seriously.

If you want to use a power that takes on the idea of transforming yourself into beast-man hybrids or even just taking on beast aspects like claws, heightened senses, wings, etc. then that's fine, I'm all up for that since it does fit into the universe of infamous :).